Elongate flexible workpieces, such as guidewires and catheters, are often coated to provide a desired property or characteristic, such as enhanced lubricity, improved biological compatibility or rust resistance. The coating is commonly applied by dipping the workpiece into a coating solution, removing the workpiece from the coating solution, and curing the coating.
Typical dip coating equipment employs coating tubes to retain the coating solution and guide the flexible workpieces as they are dipped into the solution. The top of each coating tube is usually equipped with a funnel for facilitating introduction of a workpiece into the coating tube. The coating tubes are commonly straight vertical tubes having a length sufficient to accommodate the longest workpiece to be coated.
While generally effective for coating elongate flexible workpieces, such equipment is rather bulky, arduous to use as the operator must repeatedly reach up, often above his/her head, to mount and dismount the workpieces, and requires substantial quantities of often expensive coating solution to “prime” the system, resulting in considerable waste.
In an effort to overcome these drawbacks, dip coating equipment has been designed with spiral or helical coating tubes submerged in a common reservoir of coating solution. One such coating apparatus is disclosed in United States Published Patent Application 20060210699.
While overcoming many of the drawbacks associated with straight-tube dip coating equipment, it has been discovered that coiled-tube dip coating equipment does not work well with certain types of elongate flexible workpieces as such workpieces are not susceptible to being pushed or threaded along the length of a coiled coating tube, resulting in incomplete coating and/or a kinked workpiece.
Accordingly, a continuing need exists for dip coating equipment capable of consistently and efficiently coating a wide variety of elongate flexible workpieces while using minimal coating solution to prime the system and permitting an operator to mount and dismount workpieces at a comfortable height.